Mrs Hayes and her family have participated in the event for four years.

"My husband and I enjoy the challenge on the day, and it's nice for the kids to get involved too," she said.

"My daughters were both just one year old when they started the Splash for Cash, and at three and four years old this year, they'll be joining in again." The swimathon is an annual event to raise funds for the Royal Institute for Deaf and Blind Children, which helps children with impaired hearing and sight through education, support, and research.

"When the kids first swam they had no idea what the Splash for Cash was but now my eldest understands that we're swimming to raise funds for children whose eyes or ears don't work like hers," Mrs Hayes said.

"She is learning that not everyone is the same, which is a great life lesson."

Kirsten is a swimming coach. She and her husband aim to raise $1000 through the swim.

The institute supports more than 970 children with significant hearing and vision impairment and must raise $2.5 million each month to maintain its programs.

Last year more than 100 people swam about 368 kilometres and raised $50,000.

The event will be held on Saturday, April 9 at the Sydney Olympic Park Aquatic Centre, from 8am to 3pm.

Donations can be made at ridbc.org.au/donate or at event.splashforcash.com.au/kirste n_hayes.

Registrations: splashforcash.com.au or 9872 0329.